Crowding occurs when the perception of a suprathreshold target is impaired by nearby distractors and it reflects a fundamental limitation on visual spatial resolution. Crowding limits music reading, since each note is crowded by adjacent notes and the five-line staff. We tested whether music reading experts have improved spatial resolution for musical notation. Twenty music reading experts and twenty novices were presented briefly with stimuli composed of a line and a dot in parafoveal region, where they judged whether the dot was on or off a line. In different blocks, these baseline stimuli were crowded by four additional staff lines or by two flanking dots, and we compared the Weber contrast threshold for 75% discrimination accuracy for the baseline and crowded conditions. Experts experienced a smaller crowding effect than novices for both crowding by staff lines or crowding by flanking notes. The magnitude of both types of crowding was predicted by individual music reading ability, measured by perceptual fluency with four-note sequences. In contrast to recent suggestion that crowding is independent of object category (Pelli & Tillmann, 2008), similar expertise effects were not found for non-musical stimuli (Landolt Cs): the reduced crowding effect in experts was specific to musical stimuli. The magnitude of both types of crowding was predicted by individual selectivity for notes for the N170 (120–200 ms) component but also the C1 (40–60 ms) component, measured with ERPs in a separate experiment in half of the participants. This suggests that the expertise effects in visual spatial resolution specific to musical notation may be related to changes as early as V1, consistent with a recent fMRI study showing expertise effects for musical notation in V1 (Wong & Gauthier, 2010) and with theories relating crowding to mechanisms in multiple visual areas (Fang & He, 2008; Levi, 2008; Millin, Arman, & Tjan, 2010).

This work was supported by the JSMF and NSF (SBE-0542013) and the Vanderbilt Vision Research Center (P30-EY008126).